Electric-railway system.



N0. 7l2,96l. Patented Nov. 4, I902.

W; B. POTTER. ELECTRI G BAILW AY SYSTEM.

(Application flied Mar. 5, 1900.)

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No. 7l2,96l. Patented Nov. 4, I902.

W. B. POTTER.

ELECTRIC RAILWAY SYSTEM. (Application filed'm'ar. 5, 1900 (No Model.) 3 Sheets-Shea1 2.

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Witnesses I Inventor.

W I I William Spotte I fltty.

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No. 712,91. 'Patnted Nov. 4, I902. vW. B. POTTER.

ELECTRIC RAILWAY SYSTEM.

(Application filed Mar. 5, 1906. (No Model.) 3 sheets-sheaf a.

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\VILLIAM B. POTTER, OF SCHENECTADY, NElV YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC-RAILWAY SYSTEM.

SPECIFICATION forming part of Letters Patent No. 712,961, dated November 4, 1902.

I Application filed March 5, 1960. serial No. 7,260. (No model.)

To all whom it mag concern; u w formers or may consist of groups of single Be it known that I, WVILLIAM l3. POTTER, a phase transformers. In either case they are citizen of the UnitedStat es esidingat Schenprovided with two sets of secondary coils S ectady, county of Schenectady, State of New ands. Assuming that a current having a po- 55 5 York, have invented'certain new and useful tential of ten thousand volts is maintained in Improvements in, Electric-Railway Systems, the mains, the sccondarys is constructed to (Case No. 1,067,) of'which the following is a supply current to the working conductors T,

specification. T, and R at a lower potential-for example,

This invention relates to methods of curone hundred 'volts--and when the collectors 6.)

to rent-supply for electric railways in general, of the car engage with these working conand with especial reference to surfac'e-conductors the electromagnetic switch W is actact systems, in which it is not desirable to tuated by the low-potentialcurrentto disconmaintain current of high potential pertnanect the secondary s from the working on nently upon the working conductors, which ductors T T and to connect the latter with 6 are engaged by the collectors carried by the the secondary S, which is constructed to supcar. ply a working current of one or two thousand The object of the invention is to provide a volts, as required, to operate the car-motors. sectional-conductor alternating-current rail- In order to avoid the fixed lossesin the iron way system in which the surface-conductor cores of the primary P in the arrangement 7o sections are normally maintained ata poten; shown in Fig. 1, the method illustrated in' tial not inimical to animal life and in which Fig. 2 has been devised. In this case a small the potential of these sections can be autotransformer has its primaryp permanently matically increased to the desired degree for connected to the mains and its secondary 8 operating the car-motors by the passage of permanently connected to the. working con- 25 the car which carries the motors. Thisob ductors. A large transformer has its priject is obtained, in conjunction with the-admaryPnormallydisconnected from the mains vantageous feature of reducing the fixed and its secondary S normally electrically inlossesgf transformer-cores, in the manner de: dependent of the working conductors. Each scribed in the patentto I erranti,No.4O9,7 75, transformer supplies current to the working o August271SS9f conductors at the same high potential, and The invention herein may also he applied when the working conductors are engaged by to systems other than railway systems. the collectors on the car the electromagnetic Figures 1 and 2 are diagrammatic illustra switch'W' connects the transformer P S with tions of certain features of my invention, and the mains and working conductors, so that 35 Figs. 3 and t are diagrams illustrating the apthe two transformers supply current to the plication of these features with others. working conductors in parallel. This ar- In the particular system illustrated three rangement has, however, the objection that mains L, M, and N are shown, which are snpcurrent of high potential is always supplied plied with current from any suitable source to the working conductors, and to obtain the 4c of three-phase alternating current; but the advantages of both the arrangements shown invention is not limited in its application to in Fig. l and Fig. 2 that shown in Fig. 3 has a currentof any specific number of phases. been devised. In this case the smalltraus- In Fi'g. l, P'repres'ents the primary of a former normally-supplies current at lower three 1 phase transformer permanently conpotential to the working conductors than does 45 nected to the mains 12,11, and N. A secthe large transformer, and when the workondary s cooperateswith the. primary P to ing conductors are engaged by the collectors normally supply three-phase current of low carried by acar the high potential transpotential 'tothe conductor-sections T T and former,which is normally disconnected from to one or bothof the track-rails R, which rails the mains and working conductors, is opera- I03 50 serve as the third conductor. These transtively connected therewith and the secondary formers may be single multiphase transs of the low-potential transformer is cut out.

The core losses of the primary 1) of the lowpotential transformer are not regarded as serious; but, if necessary, the electromagnetic switch W could be adapted to cut out this primary 1) when the high-potential transformer is connected to the mains and working conductors. Itis necessary to cut out the low-potential transformer when the highpotential one is cut in, because otherwise there would be a short circuit around both transformers. It is not essential that both the primary P and secondary S be normally cut out, as the arrangement would be operative and economical if only the primary P be normally cut out.

In the arrangement shown in Fig. 4 the necessity of cutting out the small or low-potential transformer is obviated by compounding it in such manner that when thelarge or highpotential transformer is cut in the low-potential transformer will supply current to the working conductors at a higher potential than it normally does and at the same potential as the current supplied by the high-potential transformer. This is accomplished in the following manner: The primaryp of the lowpotential Transformer is permanently connected with the mains. The secondary s of the low-potential transformer and the secondary S of the high-potential transformer are permanently connected in parallel with the working conductors T, T, and R. The core losses in the secondary S when thus connected in parallel with the low-potential secondary s will not ordinarily be serious; but if they should prove to be so under peculiar conditions I wish it to be understood that the secondary S maybe connected as shown in Fig. 3. Independent secondary coils s are connected in series with the secondary s of the low-potential transformer, and primaries p, normally disconnected from the mains, are adapted to cooperate with said independent or auxiliary coils. The primaryPof the highpotential transformer is also normally disconnected from the mains.

Let us assume, for example, that a current ofonehundred voltsis normallysupplied from the secondary s to the working conductors, and, as before, that the current of ten thousand volts is maintained on the mains, and that, furthermore, the transformersp' s, the primaries p of which are normally disconnected from the mains, are adapted to supply acurrentof nine hundred volts to the working conductors,while the transformerP S supplies one thousand volts to the working conductors. Then when the working conductors are engaged by the collectors of a car the electromagnetic switch W will be actuated by the low-potential current to connect the primaries p and the primary P with the mains, whereupon the compound transformer built up around the primaryp will supply current at one thousand volts to the working conductors in parallel with the large transformer P S,

which is also supplying current at one thousand volts.

The small transformer will operate in the manner described if the legs of the primary P are disconnected from the lines leading from the electromagnetic switch W to the primaries p, and hence the high-potential transformer P S may be dispensed with, if desired, since the small transformer completely fulfils the requirements of maintaining normally a low potential on the working conductors and supplying a working current of higher potential when a car traverses that portion of the road which is controlled by that transformer. of the compound transformer should be suitably modified for the purpose by the use of larger cores and windings of larger cross-section than those used when the high-potential transformer is a part of the system. The auxiliary coils s will normally operate as reactances in the transformer, but only during the time of flow of the low-potential current, and will not seriously atfect the desired results.

In practice it is preferred that at least two of the working conductors T and T be divided into sections A B B, the current supplied to each section being controlled by the methods described. The track-rails B may be permanently connected to one side of the secondary three-phase system, as shown and described above.

'lhe'combination is claimed, broadly, herein of a transformer secondary which supplies current at low potential to the working conductors, a high-potential transformer-secondary which is cut into circuit automatically, and means for preventing a short circuit. The specific means for preventing short-circuiting illustrated in Fig. 4 is also claimed herein; but the means shown in Figs. 1 and 3 is not claimed, as it forms the subject-matter of a divisional case.

\Vhat I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In an electric-railway system, the combination with the feeders and working conductors, of a transformer adapted to normally supply current of low potential to said conductors, a second transformer, and an electromagnetic switch actuated by the low-potential transformer, upon the passage of a car, to connect the second transformer so that a current of higher potential will be supplied to said conductors.

2. In an electric-railway system, the combination with the feeders and working conductors, of a transformer normally supplying current of low potential to said conductors, a second transformer, and an electromagnetic switch actuated by the low-potential transformer, upon the passage of a car, to cooperate with the first transformer to supply a working current of higher potential to said conductors.

In this case the construction- In an electric-railway system, the combination with the feeders and working eonductors, of a compound transformer adapted to normally supply current of low potential to said conductors, a second transformer normally operatively disconnected from the feeders, and an electromagnetic switch operated by the low-potential transformer, upon the passage of a car, for causing both transformersto supply a working current of higher potential in parallel to said conductors.

4. In an electric-railway system, the combination with the feedersand working conductors, of a compound transformer having some coils adapted to normally supply current of low potential'to said conductors, and having normally inoperative coils adapted to cooperate with said coils to supply Working current of higher potential to said conductors,

and an electromagnetic switch operated by said low-potential current, upon the passage of a car, to cause said cooperating coils to become operative.

5. In a system of distribution, the combi nation with the mains, of a transformer having its primary connected therewith, independent primary coils normally operatively disconnected from the mains, independent secondary coils in series with the secondary coils of said transformerand cooperating with said independent primary coils, and means for causing the independent primary coils to be operatively connected with the mains.

6. In an electric railway system, the, combination with the feeders, of working conductors,a transformer having its primary connected with the feeders and its secondary with the working conductors,independent primary coils normally operatively disconnected from the feeders, independent secondary coils in series with the secondary coils of said transformer and cooperating with said independent primary coils, an electromagnetic switch operated by the current in the secondary of said transformer, for connecting said independent primary coils to be operated by the feeders.

7. In an electric-railway system, the combination with the feeders, of working conductors, a low-potential transformer connected with the feeders and working conductors, a transformer of relatively higher potential and normallyinoperative bythefeeders, independent primary coils normally operatively disconnected frotn the feeders, independent secondary coils in series with the secondary of saidlow-potential transformer and cooperating with said independent primary coils, and an electromagnetic switch operated by the low-potential current, for connecting said independent coils and the high-potential transformer so as to be operated by the feeders.

8. In an electric-railway system, the combination with the feeders, of working conductors, a low-potential transformer connected with the feeders and working conductors, a transformer of relatively high potential normally operatively disconnected from the feeders, and having its secondary connected in parallel with the secondary of the low-potential transformer, independent primarycoils normally operatively disconnected from the feeders, independent secondary coils in series with the secondary coils of the lowpotential transformer and codperating with said independent primary coils, and an electromagnetic switch operated by the low-potential current to connect the primary of the high-potential transformer and the independent primary coils so as to be operated by the feeders.

9. In an electric-railway system, the combination with the feeders and working conductors, of a transformer connected with the feeders and said conductors, and adapted to normally supply current of low potential to said conductors, and adapted to be compounded to supply higher potential, asecond transformer adapted to supply current of higher potential to said conductors and normally inoperative by the feeders, and an electromagnetic switch operated by the lowpotential current, on the passage of a car, to connect the high-potential transformer to be operated by the feeders and to cause the first transformer to supply current of the same potential as the high-potential trahsformer to the working conductors,in parallel with the high-potential transformer.

10. An alternating-currentelectric-railway system, which comprises high-potential feeders, working conductors, a transformer secondary cooperating with the feeders to normally supply a current of' low potential to the working conductors, and another transformer secondary cooperating with the feeders to supply current at a higher potential than the first secondary, to the working conductors, during the passage of a car thereover.

11. In an alternating-current system, the combination with the mains, of a transformer secondary adapted to cooperate with the mains to supply current of lower potential than that flowing in the mains, a second transformer secondary adapted to supply current of higher potential than that supplied by the first secondary, and means controlled by the first secondary for connecting the second secondary in circuit and preventing a short circuit through the first transformer.

12. In an electric-railway system, the combination with the feeder and sectional Working conductors, of a transformer adapted to normally supply current of low potential to said conductors, a second transformer adapted to supply current of higher potential to said conductors, and an electromagnetic switch actuated when a car closes the circuit of the first secondary, to cut the second sec ondary into circuit and prevent a short circuit of the first secondary.

13. In a system of distribution for alternating currents, the combination with the mains ofa transformer secondary cooperating therewith to normally supply current of lower potential than that of the feeders, and another transformer secondary cooperating with the feeders and with the first secondary, to automatically supply current of higher potential than that supplied by the first secondary, when required.

14. In a system of distribution for alternating currents, the combination with the mains or feeders, of a transformer secondary cooperating therewith to normallysupply current of lower potential than that of the feeders, another secondary cooperating with the feeders to supply current of higher potential than that supplied by the first secondary, and an electromagnetic switch operated by the lowpotential current to cause the other secondary to become operative.

15. In a system of distribution, the combination with the mains, of a transformer 00- operating therewith to supply current of lower potential than that flowing through the mains, a second transformer of higher otential than that supplied by the first, and normally disconnected from the mains, and an electromagnetic switch operated by the low-potential current, for connecting the second transformer with the mains.

16. A ti ansformer having, auxiliary coils in series with its secondary, and independent primary coils adapted to cooperate with said auxiliary coils.

17. A transformer having its primary and secondary windings adapted to be normally connected to the mains and load, auxiliary coils in series with its secondary, independent primary coils, normally disconnected from the mains and adapted to cooperate with the auxiliary coils, and a switch for connecting the independent primary coils with the mains.

18. In an electric-railway system, the combination with the feeders and working conductors, of a compound transformer comprising coils adapted to normally supply low-potential current to said working conductors, and auxiliary coils adapted to cooperate with said coils to supply current to said working conductors at a higher working potential when a car is on said conductors.

19. In an electric-railway system, the combination with the feeders and working conductors, of a transformer adapted to supply current at low potential to said conductors normally, a transformer adapted to supply current at high working potential to said conductors during the passage of a car, and means for preventing a short circuit through said transformers.

20. In an electric-railway system, the combination with feeders and working conductors, of a transformer having part of its primary directly connected with said feeders and its secondary connected with said working conductors, whereby it may normally transmit current of low potential to the latter, and means actuated by said low-potential current for connecting the whole of said primary to said feeders, whereby current of higher potential is supplied to the working conductors during, the passage of a car.

21. In an electric-railway system, the combination with the feeders and working conductors, of a transformer adapted to normally supply current of low potential to said conductors, a second transformer, and an electromagnetic switch actuated by the lowpotential current, upon the passage of a car, to connect the second transformer so that a current of higher potential will be supplied to said conductors, said switch being maintained in the position to which it has been moved by the current flowing from the secondary of the second transformer.

22. In an electric-railway system, a source of high-potential current, a source of lowpotential current independent of the car, working conductors from which the current for operating the car-motors is collected, said low-potential source being normally connected to, and said high-potential source being normally disconnected from said working conductors, and means operated by the lowpotential current for connecting said highpotential source with said working conductors upon the passage of a car.

23. In an electric-railway system, a source of high-potential current, a source of lowpotential current independent of the car, working conductors from which the current for operating the car-motors is collected, said low-potential source being normally connected to, and said high-potential source being normally disconnected from said working conductors, and electromagnetic switches operated by current from said low-potential source to connect said high-potential source to the working conductors upon the passage of a car.

24. In an alternating-current system, the combination with high-potential feeders and working conductors, the track rail or rails forming one of said conductors, of a low-potential transformer normally operatively con nected with said feeder and working conductors, a high-potential transformer normally operatively disconnected from said conductors, and means for connecting said high-potential transformer to said working conductors.

In witness whereof I have hereunto set my hand this 2d day of March, 1900.

WILLIAM B. POTTER.

\Vitnesses:

BENJAMIN B. HULL, MABEL H. EMERSON. 

